Niacin

• Coenzymes forms of niacin function in many cellular metabolic pathways

• When cell energy is being utilized, a niacin coenzyme is used

• Synthetic pathways in the cell-those that make new compounds-also often use a niacin coenzyme (this is especially true for fatty acid synthesis)

• Most every cellular metabolic pathway uses a niacin coenzyme, a deficiency causes widespread changes in the body

• The group of niacin deficiency symptoms is known as pellagra, which means rough or painful skin

NIACIN SOURCES AND NEEDS

• Poultry, ready-to-eat cereals, beef, wheat bran, tuna and other fish, asparagus, and peanuts

• Coffee and tea also contribute some niacin to the diet

• Very heat stable; little is lost in cooking

• We can synthesize niacin from the amino acid tryptophan

• We synthesize 50% of the niacin we need

• Adult RDA of niacin is 14-16 milligrams per day

UPPER LEVEL FOR NIACIN

• 35 milligrams per day

• effects include headache, itching, and increased blood flow to the skin, causing a general blood vessel dilation or flushing in various parts of the body

• long run: GI tract and liver damage is possible, so any use of megadoses, including large doses recommended for treatment for cardiovascular disease, requires close physician scrutiny

Category: Biochemistry Notes